It’s quite simple really.
You need some vaseline - preferably the white type.
Lubricate your dick, then place the bottle at the top end, then turn the bottle in an anticlockwise direction. The thread in the bottle will gouge out the head to accomodate the thread, and fix it in that way. It will then be necessary to get hold of the bottle on each side and pull the sides away from each other. This will cause the vacuum and your dick will expand
When finished turn the bottle in a clockwise direction and the bottle will unscrew itself.
Trying to fix the bottle steady and then turning yourself in a horizontal cartwheel probably wouldn’t work, as the bottle would be too wobbly.
I must point out though that you must perform this exercise with caution, as you can easily tear the bottle top from the body of the bottle.
Can anyone think of a name for this unique new routine?